分散固相萃取-液质联用法检测玉米中4种农药

Determination of 4 Pesticides in Corns by Liquid Chromatography-Tandem Mass Spectrometry with Dispersive Solid Phase Extraction

利用分散固相萃取(QuEChERS)改良技术建立了玉米中多菌灵、吡虫啉、乙草胺、异丙甲草胺残留的液相色谱-串联质谱分析方法。样品经1%甲酸乙腈提取,采用N-丙基乙二胺(PSA)和十八烷基键合硅胶(C_(18))共萃取净化,C_(18)色谱柱分离,0.1%甲酸-乙腈为流动相梯度洗脱,质谱采用电喷雾正离子(ESI^+)模式电离,多离子检测模式(MRM)定性,基质标准曲线外标法进行定量分析。结果表明:玉米基质中多菌灵、吡虫啉、乙草胺、异丙甲草胺在0.5μg/kg^100μg/kg浓度范围内,具有很好的线性关系,其相关系数(R)均大于0.995。在3个加标浓度下,4种农药的平均回收率在88.0%~112.0%之间,相对标准偏差(RSD,n=5)不大于9.5%。该方法对多菌灵、吡虫啉、乙草胺和异丙甲草胺的检出限分别为0.025、0.15、0.15μg/kg和0.025μg/kg,满足玉米中4种农药残留分析的要求。

A simple pesticide analysis method was developed for the determination of carbendazim, imidacloprid, acetochlor and metolachlor in corns based on dispersive solid phase extraction procedure combined with liquid chromatography-positive mode electrospray ionization-tandem mass spectrometric（ LC-MS/MS）. The analytes were extracted with acid acetonitrile and cleaned up by primary secondary amine（ PSA） and octadecyl silane（C（18））. Qualitative and quantitative analyses were carried out for four analytes under the positive scanning models after the chromatographic separation on reversed phase C（18） column with an gradient elution program of acetonitrile and 0.1 % formic acid aqueous solution. The coefficient of determination（ R） was 0.995 within the calibration linearity range of 0.5 μg/kg-100 μg/kg for the four peaticides. The average recoveries of carbendazim, imidacloprid, acetochlor and metolachlor in corn samples were in the range 88.0 %-112.0 %with associated RSDs（ n=5） ≤ 9.5 % at the three spiked level. The limits of detection（ LOD） of four analytes were 0.025,0.15, 0.15 μg/kg and 0.025 μg/kg, respectively. The method could meet the determination requirements of these four pesticides in corns.